adds coupline configuration file

config/coupling.yaml

+## documentation on coupling configuration file can be found here:
+##  https://dkrz-sw.gitlab-pages.dkrz.de/yac/dd/dfa/yaml_file.html
+
+## The following part will instruct YAC to write out the elmer grid into a
+## netcdf file as it was understood by YAC. This can help debugging the grid
+## definition.
+## The resulting netcdf file can be converted to vtk with the following command:
+##   yac_build_dir/tools/debug_grid2vtk.x \
+##     -n elmer_grid -f elmer_grid.nc -o elmer_grid.vtk
+## This vtk file can be easily visualised using Paraview.
+# debug:
+#   output_grids:
+#     - grid_name: elmer_grid
+#       file_name: elmer_grid.nc
+
+start_date: 2008-03-09T16:05:07
+end_date: 2008-03-10T16:05:07
+timestep_unit: second
+calendar: proleptic-gregorian
+# coupling:
+#   ## ICON -> Elmer/Ice
+#   - src_component: atmo
+#     src_grid: icon_atmos_grid
+#     tgt_component: elmer
+#     tgt_grid: elmer_grid
+#     coupling_period: 2
+#     field: temp
+#     interpolation:
+#       - nnn:
+#           n: 1